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首页> 外文期刊>Biochemistry >Biochemical characterization of phosphoryl transfer involving HPr of the phosphoenolpyruvate-dependent phosphotransferase system in Treponema denticola, an organism that lacks PTS permeases.
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Biochemical characterization of phosphoryl transfer involving HPr of the phosphoenolpyruvate-dependent phosphotransferase system in Treponema denticola, an organism that lacks PTS permeases.

机译：密闭性密螺旋体中缺乏依赖于PTS渗透酶的生物体中涉及磷酸烯醇丙酮酸依赖性磷酸转移酶系统的HPr的磷酸化转移的生化特征。

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摘要

Treponema pallidum and Treponema denticola encode within their genomes homologues of energy coupling and regulatory proteins of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) but no recognizable homologues of PTS permeases. These homologues include (1) Enzyme I, (2) HPr, (3) two IIA(Ntr)-like proteins, and (4) HPr(Ser) kinase/phosphorylase (HprK). Because the Enzyme I-encoding gene in T. pallidum is an inactive pseudogene and because all other pts genes in both T. pallidum and T. denticola are actively expressed, the primary sensory transduction mechanism for signal detection and transmission appears to involve HprK rather than EI. We have overexpressed and purified to near homogeneity four of the five PTS proteins from T. denticola. Purified HprK phosphorylates HPr with ATP, probably on serine, while Enzyme I phosphorylates HPr with PEP, probably on histidine. Furthermore, HPr(His)-P can transfer its phosphoryl group to IIA(Ntr)-1. Factors and conditions regulating phosphoryl transfer prove to differ from those described previously for Bacillus subtilis, but cross-enzymatic activities between the Treponema, Salmonella, and Bacillus phosphoryl-transfer systems could be demonstrated. Kinetic analyses revealed that the allosterically regulated HPr kinase/phosphorylase differs from its homologues in Bacillus subtilis and other low G+C Gram-positive bacteria in being primed for kinase activity rather than phosphorylase activity in the absence of allosteric effectors. The characteristics of this enzyme and the Treponema phosphoryl-transfer chain imply unique modes of signal detection and sensory transmission. This paper provides the first biochemical description of PTS phosphoryl-transfer chains in an organism that lacks PTS permeases.
机译：苍白密螺旋体和密螺旋体在其基因组内编码磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）的能量耦合和调节蛋白的同源物，但没有PTS通透酶的可识别同源物。这些同源物包括（1）酶I，（2）HPr，（3）两个IIA（Ntr）样蛋白和（4）HPr（Ser）激酶/磷酸化酶（HprK）。因为梅毒螺旋体中的酶I编码基因是无活性的假基因，并且因为梅毒螺旋体和树状体中的所有其他pts基因都被有效表达，所以信号检测和传递的主要感觉转导机制似乎涉及HprK，而不是HprK。 EI。我们已经过表达并纯化了来自T. denticola的五个PTS蛋白中的四个，接近同质。纯化的HprK可能在丝氨酸上用ATP磷酸化HPr，而酶I可能在组氨酸上用PEP磷酸化HPr。此外，HPr（His）-P可以将其磷酰基转移至IIA（Ntr）-1。事实证明，调节磷酰基转移的因素和条件与之前描述的枯草芽孢杆菌不同，但可以证明螺旋体，沙门氏菌和芽孢杆菌磷酰基转移系统之间的交叉酶活性。动力学分析表明，变构调节的HPr激酶/磷酸化酶与其在枯草芽孢杆菌和其他低G + C革兰氏阳性细菌中的同系物不同，在于在没有变构效应子的情况下被激活了激酶活性而不是磷酸化酶活性。这种酶和螺旋体磷酸化转移链的特性暗示着信号检测和感觉传递的独特模式。本文提供了在缺乏PTS渗透酶的生物中PTS磷酸转移链的第一个生化描述。

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